core/src/main/java/com/opensymphony/xwork2/config/providers/EnvsValueSubstitutor.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package com.opensymphony.xwork2.config.providers;

import org.apache.commons.text.StringSubstitutor;
import org.apache.commons.text.lookup.StringLookupFactory;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

public class EnvsValueSubstitutor implements ValueSubstitutor {

    private static final Logger LOG = LogManager.getLogger(EnvsValueSubstitutor.class);

    protected StringSubstitutor envStrSubstitutor;
    protected StringSubstitutor sysStrSubstitutor;

    public EnvsValueSubstitutor() {
        envStrSubstitutor = new StringSubstitutor(System.getenv());
        envStrSubstitutor.setVariablePrefix("${env.");
        envStrSubstitutor.setVariableSuffix('}');
        envStrSubstitutor.setValueDelimiter(':');

        sysStrSubstitutor = new StringSubstitutor(StringLookupFactory.INSTANCE.systemPropertyStringLookup());
        sysStrSubstitutor.setVariablePrefix("${");
        sysStrSubstitutor.setVariableSuffix('}');
        sysStrSubstitutor.setValueDelimiter(':');
    }

    @Override
    public String substitute(String value) {
        LOG.debug("Substituting value {} with proper System variable or environment variable", value);

        String substituted = sysStrSubstitutor.replace(value);
        return envStrSubstitutor.replace(substituted);
    }
}